HD-DVD discs use an encryption scheme known as AACS, which has a publicly-disclosed algorithm—the secret lies in the 128-bit encryption keys that are carefully guarded by the makers of HD-DVD players. A key was discovered and, this last week, posted on digg. It received over 15,000 diggs (which is a lot) before being removed at the request of the MPAA and the AACS Licensing Authority. The digg community went absolutely berserk, and for the next day or so every subsequent post was either about the key or had the key in the comments.

Back in January a program named BackupHDDVD was published. It implements the AACS algorithm but requires an encryption key as input, so at the time it was downplayed as the crack that wasn’t. But now, with the key, it works just fine. Note that AACS has a mechanism to disable keys, but it only works on future disc releases.